CD4 and Zika virus infectious disease: Although IFNAR deficient mice are known to be susceptible to ZIKV infection [32,33,34], depleting CD4 T cells from 10–12 week old IFNAR knock-out (KO) mice caused higher viral loads, more severe paralysis, and reduced survival [20], and caused lethal infection in 3-4 week old IFNAR KO mice [21].